1. Field of the Invention
The present invention generally relates to a contactor for semiconductor devices, a testing apparatus using such a contactor, a testing method using such a contactor and a method of cleaning such a contactor, and particularly relates to a contactor for obtaining an electrical contact with a semiconductor device such as a wafer, a bare chip, a BGA (Ball Grid Array), an SOP (Small Outline Package) and a QFP (Quad Flat Package), a testing apparatus and a testing method using the contactor, and a method of cleaning such a contactor.
Recently, there is an increasing need for further miniaturized, high-speed and high-density semiconductor devices. Therefore, in order to provide terminals corresponding with such semiconductor devices, efforts are being made to achieve a further fine-pitched structure of the terminals provided on the semiconductor devices. Also, in order to improve the testing efficiency of the semiconductor devices, there is a need for simultaneously contacting a plurality of semiconductor devices, for example, at a wafer level.
However, the height of the terminals of the semiconductor devices and the height of contact electrodes are varied. Therefore, it is technically very difficult to connect the contact electrodes to all of the fine-pitched terminals.
2. Description of the Related Art
FIG. 1 is a cross-sectional diagram showing a contactor 1 for a semiconductor device (hereinafter referred to as a contactor) of the related art. As shown in the Figure, the contactor 1 includes a wiring substrate 2, an anisotropic conductive sheet 4, a multilayer substrate 5, and a base member 6.
The wiring substrate 2 includes a base film made of resin and a wiring pattern formed thereon. Also, a part of the wiring pattern is provided with contact electrodes 3 to which terminals of a semiconductor device 8 (in the Figure, a wafer is illustrated as an example of the semiconductor device) are connected. The contact electrodes 3 extend to an upper surface (i.e., a surface opposite a surface provided with the contact electrodes 3) of the wiring substrate 2 via through holes or vias (not shown) formed in the base film.
The multilayer substrate 5 is a multilayer wiring printed-circuit board, which includes a substrate made of glass-epoxy whereon a plurality of wiring substrate layers provided with wiring patterns are laminated. Also, the layers provided with the wiring patterns are each electrically connected by elements such as through holes. Therefore, in the related art, the multilayer substrate 5 is made of an extremely hard material (or a material with a high rigidity).
In the contactor 1 shown in the Figure, the anisotropic conductive sheet 4 is provided between the wiring substrate 2 and the multilayer substrate 5. The anisotropic conductive sheet 4 is elastic and is conductive in a vertical direction in the Figure, so that an electric connection is established only at only at locations under pressure.
If the wiring substrate 2 is provided directly on the multilayer substrate 5 with high rigidity, it is not possible to overcome the variation of the heights of the terminals of the semiconductor device 8 or the contact electrodes 3 of the wiring substrate 2. The purpose of using the anisotropic conductive sheet 4 is to avoid such a drawback and thus positively connect the contact electrodes 3 to the plurality of terminals. Also, the wiring substrate 2, the anisotropic conductive sheet 4 and the multilayer substrate 5 constitute an integrated body.
The base member 6 is provided with a mounting portion 7 having a recessed shape corresponding to the contour of the semiconductor device 8. The semiconductor device 8 is mounted in the mounting portion 7 so as to be maintained by the base member 6.
For electrically connecting the contactor 1 of the above structure and the semiconductor device 8, the semiconductor device 8 is mounted on the mounting portion 7 of the base member 6. Then, the wiring substrate 2 is pressed onto the semiconductor device 8. Thus, the contact electrodes 3 and the terminals of the semiconductor device 8 are connected and it is possible to establish an electrical conduction between the wiring substrate 2 and the semiconductor device 8.
In FIG. 1, the contactor 1 includes the anisotropic conductive sheet 4 provided between the wiring substrate 2 and the multilayer substrate 5. However, another example of the contactor of the related art may include an anisotropic conductive sheet provided between a wiring substrate and a semiconductor device.
Also, there is provided a contactor with greater contact pressure (adhesive force) between the wiring substrate and the semiconductor device. This is achieved by providing a seal member between a base member on which the semiconductor device wafer is mounted and the wiring substrate. A negative pressure is built up in an area sealed with the sealing member so that the wiring substrate will be pressed against the semiconductor wafer under atmospheric pressure.
There are two forces required for connecting the wiring substrate 2 to the semiconductor device 8. One of the forces is a pressure required for connecting the contact electrodes 3 provided on the wiring substrate 2 to the terminals of the semiconductor device 8. This force is hereinafter referred to as a contact pressure. The other force is a pressure required for maintaining the wiring substrate 2 in position with the base member 6. This force is hereinafter referred to as a position maintaining force.
Since the contact pressure and the position maintaining force have different functions, as has been described above, it is necessary to adjust each force to a strength appropriate for the respective functions.
That is to say, the contact pressure should be adjusted for providing a good electrical connection between the contact electrodes 3 of the wiring substrate 2 and the terminals of the semiconductor device 8, thus preventing any deformation of the contact electrodes 3 and the terminals. Also, the position maintaining force should be adjusted to a value sufficient for preventing any offset of the positioning of the wiring substrate 2 and the base member 6 when there is a certain external force being applied.
Therefore, for electrically connecting the wiring substrate 2 and the semiconductor device 8 in an ideal state, normally, it is necessary that the strength of the position maintaining force be greater than that of the contact pressure.
However, with the contactor 1 of the related art, the contact pressure and the position maintaining force cannot be adjusted independently. With such a structure, the wiring substrate and the semiconductor devices may be electrically connected by the above-described negative pressure. Then, if the negative pressure is released in order to release the contact pressure, the position maintaining force is also released. Accordingly, there is a drawback that the wiring substrate and the semiconductor devices are offset from the predetermined positions.
Also, with the contactor 1 of the related art, the contact pressure and the position maintaining force are the same force. When it is attempted to increase the position maintaining force, the contact pressure will also be increased, thus creating a risk of the terminals of the semiconductor device being seriously damaged.
Further, with the contactor 1 of the related art, the flexibility of the wiring substrate 2 is provided by the elasticity of the anisotropic conductive sheet 4 and thus is limited to such elasticity. Therefore, it is not possible to compensate for any variation of heights of the contact electrodes 3 and the terminals which variation exceeds the elasticity of the anisotropic conductive sheet 4. Accordingly, when there is any variation of the heights of the fine-pitched terminals, the contact electrodes 3 cannot be connected to all of the terminals of the semiconductor device 8.
Accordingly, it is a general object of the present invention to provide a semiconductor device contactor which can solve the problems described above. It is another and more specific object of the present invention to provide a semiconductor device contactor which can securely connect contact electrodes to a semiconductor device having fine terminals and can prevent the terminals and the contact electrodes from being damaged.
In order to achieve the above objects according to the present invention, a semiconductor device contactor includes a base unit for holding a semiconductor device provided with a plurality of terminals and a wiring substrate provided with contact electrodes at positions corresponding to at least some of the terminals. The contact electrodes and the terminals are electrically connected when the wiring substrate is held on the base unit.
The semiconductor device contactor further includes: a position maintaining force applying mechanism for applying a position maintaining force between the base unit and the wiring substrate; and a contact pressure applying mechanism for applying a contact pressure between the semiconductor device and the wiring substrate. The position maintaining force applying mechanism and the contact pressure applying mechanism are operable in an independent manner.
With the contactor described above, it is possible to prevent a mutual influence between the contact pressure and the position maintaining force. Thus, it is possible to independently applying an optimum position maintaining force and an optimum contact pressure. Accordingly, a precise positioning between the wiring substrate and the base unit and a stable contact state between the semiconductor device and the wiring substrate can be achieved.
It is still another object of the present invention to provide a testing device for obtaining a stable contact force.
In order to achieve the above object, the testing device includes a semiconductor device contactor as described above and a chamber for accommodating the semiconductor device contactor. The chamber is constructed such that its internal atmosphere may be of a positive pressure.
With the testing device described above, even if the contact pressure resulting from the negative pressure is insufficient, the contact pressure can be relatively increased by applying a high pressure in an atmosphere of the chamber. Thus, a stable contact pressure can be obtained.
It is yet another object of the present invention to provide a method of testing a semiconductor device using a semiconductor device contactor described above, which method can implement an accurate positioning and a secure connection of the contact electrodes of the wiring substrate to the terminals of the semiconductor device.
In order to achieve the above object, the testing method includes the steps of:
a) calculating a position correction value by recognizing the positions of the terminals and the electrodes, and then calculating the offset between the positions of the terminals and the contact electrodes;
b) positioning the wiring substrate with the base unit based on the position correction value;
c) driving, after the step b), the position maintaining force applying mechanism for applying a position maintaining force between the wiring substrate and the base unit;
d) driving the contact pressure applying mechanism for applying a contact pressure between the wiring substrate and the semiconductor device; and
e) testing the semiconductor device.
With the testing method described above, an accurate positioning can be achieved by the steps a) and b). Also, a secure connection of the contact electrodes to the terminals can be achieved since, after positioning, first, the wiring substrate and the base unit are fixed by means of the position maintaining force applying mechanism and, then, the contact pressure is applied between the wiring substrate and the semiconductor device by means of the contact pressure applying mechanism.
It is yet another object of the present invention to provide a method of cleaning the semiconductor device contactor described above which method can remove unwanted layers disposed on the contact electrodes and thus achieve a stable contact state.
In order to achieve the above object, a method of cleaning a contactor for semiconductor devices, particularly cleaning contact electrodes provided on a wiring substrate provided on the contactor, includes the steps of:
a) providing a cleaning member instead of the semiconductor device on the base unit, such that the cleaning member is in contact with the contact electrodes for cleaning the contact electrodes;
b) holding the wiring substrate on the base unit by driving the position maintaining force applying mechanism;
c) repeatedly driving and ceasing the contact pressure applying mechanism while the wiring substrate is held on the base unit.
With the cleaning method described above, unwanted layers disposed on the contact electrodes can be remove and thus a stable contact state can be achieved.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.